Radiator fan motor on the way out?

[Falcon_LS]

Been noticing something unusual for the past few days with my Grand Marquis. I monitor coolant temperature with a ScanGauge-II, and granted the weather is pretty hot - 130+ F - I'm beginning to think my fan motor might be on its way out.

In stock form with a 190 F thermostat, the high speed function would kick in when coolant temperature hit 212 F. As it stands, I'm running a 180 F thermostat with the EEC programmed for it. Although the low speed function is running most of the time, I'm seeing crazy figures like 218 F with the AC clutch engaged. If I'm stuck in traffic, I sometimes turn the AC off and coolant temperature starts dropping at a snail's phase. At 75 MPH on the freeway, 216 F is the average coolant temperature and I haven't heard that wind tunnel noise when the fan kicks into high - not even when the AC is on.

I've checked the relay, which is fine. I'm going to wire it directly and see if the fan works on high speed. Just wondering if anyone has any other thoughts. Everything in the cooling system, except the fan, was replaced when I built the motor.

 

[andyd]

check its draw with an ammeter. Sorta related, by cleaning and lubing the aux fan on my 528e, I reduced its draw by nearly an amp. Once I figured out the nut holding the fan on was a lefty, it was easy to take apart. YMMV

 

[Colt45ws]

Yeah, if you can measure the draw. Usually when they get bad, they start blowing fuses.

 

[SHOZ]

Make sure the connectors are clean and no corrosion. The high amperage will aggravate any connector issue.

 

[RF Overlord]

At 75 MPH you shouldn't need the fan to come on at all...maybe something blocking your airflow? Detritus between the condenser and the rad?

 

[HerrStig]

The relay contacts are worth checking.

 

[Colt45ws]

Originally Posted By: RF Overlord
At 75 MPH you shouldn't need the fan to come on at all...maybe something blocking your airflow? Detritus between the condenser and the rad?


The program has a function that shuts off the fan above a specific vehicle speed as it does more harm than good. IIRC its 45mph but I didnt look.

 

[Kuato]

I've seen similar things happen when there's a bit of buildup on the inside of the radiator, which reduces cooling power. Every spring there are a rash of posts about "it's been fine all winter but now that it's hot with AC on...".

So if it's not the fan on your 15 year old GM, then I'd look at replacing the radiator....it might not be that bad for lower temps, but at 130°F any reduced capability will show up quickly.

 

[Chris142]

Clean the condenser and radiator fins

 

[Falcon_LS]

Thank you for the responses.

I checked the fan and the high speed function is indeed working, but I haven't checked the draw. Also cleaned up the connectors with electrical contact cleaner, although they appeared clean. I did wash the condenser/radiator assembly, which did considerably drop coolant temperature there and then, but it's still relatively high when driving. I guess it might be directly related to the weather conditions because my Envoy, Expedition and Explorer are showing the same range of coolant temperatures. It hit 140 F yesterday.

That said, I failed to mention the only thing that's 15 years old on this car is pretty much just the body. It has a built motor and transmission and the cooling system is new.

 

[Merkava_4]

I think it's related to the 180 F thermostat and the reprogram.

 

[Colt45ws]

It is probably just the ambient. Ive never experianced that sort of temperature. The higher the ambient, the higher the coolant needs to be to dump the heat. Ive driven in 105F and itll run about 200F , so thats 95F above ambient. 130+95=225F

So, yours is doing better than my car with its original cooling system. ( As expected.)

Your car has the PI oil cooler, correct? You might consider removing it and going with a OTA cooler. One with its own fan. I had been thinking about mounting one on my other car between the radiator mount and the #2 cross member. Kind of at an angle with a little bit of a duct to pull air from the front of the radiator. This will remove all the heat the oil system is dumping into the coolant. Basically increase the size of your radiator.

 

[RF Overlord]

Originally Posted By: Falcon_LS
It hit 140 F yesterday.
As a gentleman of rotund proportions, that temperature would cause me to experience much distress...

 

[Merkava_4]

Originally Posted By: Falcon_LS
It hit 140 F yesterday.


How do people in Kuwait manage to survive those temperatures ?

 

[The_Eric]

It's a DRY heat...